Above article highlighted as an Editorial Feature [http://jeb.biologists.org/content/215/15/v.2.full Hydrophobicity Counts in Large Amounts] in the ‘Outside JEB’ section of ''Journal of Experimental Biology''.

Research interests

Adaptive and evolutionary physiology of vertebrate animals. More specifically I am interested in their adaptation to extreme cold and heat, and how their physiological systems have evolved to allow them to exploit such niches. The model system that I have been using is that of the proteins in the eye lens. The proteins are called “crystallins” and play an important role in light refraction. Most vertebrates (excluding some birds) have three kinds of crystallins; alpha (α), beta (β) and gamma (γ). Alpha crystallin is also a type of small heat shock (sHsp) protein and comes in at least two flavours (isoforms). One of these α isoforms can be found widely expressed outside the eye lens and has important roles as a stress protein in a number of tissues. The β and γ crystallins are part of the same super-gene family, but presently there are no known non-refractive structure/function roles. Adaptation of ectothermic vertebrate lenses to cold is of interest to me as means of modeling not only lens cataracts, but to modeling globular protein stability. Cold-cataracts in mammalian lens have been used to model senile cataracts. Many ectothermic vertebrates that are cold-adapted do not show a cold-cataract (see interest #2). Thus, the appearance or absence of a lens cataract is a rare example of a protein model system that allows investigation into evolutionary adaptation and physiological importance of globular non-enzymatic protein stability.

A second major interest of mine is molecular (amino acid) adaptations that occur in globular (structural) proteins which impart a long-term stability. This is essentially an extrapolation of the first research interest to non-lenticular proteins. However, lenses from ectothermic animals are ideal systems to study this problem as these animals (including their lenses) are thermally adapted to their native environments (whether cold or hot). Because lens proteins are conserved amongst vertebrates these structure/function comparisons are valid. Human lenses do not show thermal adaptation thus providing an excellent comparative basis to determine the structural basis of the instability in many mammalian lenses. In fact, human lenses exhibit a so-called “cold-cataract” at temperatures below +20°C, which has been used to model not only senile (age-related) cataracts, but also other protein condensation diseases such as Alzheimer's Diseases and Sickle Cell Anæmia. The common thread through each of these pathologies are instabilities in the globular/structural proteins. By using a novel cross-species chaperone assay developed in my lab (Kiss et. al., 2004), coupled with phylogenetic analysis (Kiss et. al., 2008), and mass-spectrometry proteomics approaches, we are identifying individual crystallins, their residue changes and their post-translational modifications that we believe have increased the stability of the crystallins and thus maintaining lens transparency.

Sensory systems in the acclimatory response. The ability of an animal to change its physiology dependent on environmental cues is a complex and multifaceted process. Whether the animal is a fish, frog, bird, rat or human, an acclimatory response is something that occurs readily everyday in animals. I am currently engaged in studies using the North American wood frog Rana sylvatica to determine the changes in protein expression permitting these frogs to be able to freeze solid, thaw and survive. This overwintering strategy is rare among higher vertebrates and demonstrates an extreme example of physiological, biochemical and molecular adaptation. Future plans to employ cDNA arrays and genome technologies are underway that will further elucidate the mechanisms by which these animals are able to sense their environment thereby prompting a freeze competent state in the frogs.